Synchronizing system



pa sed Oct. 11, 1932 uu-rrso'sm'rss PATENT OFFICE WILLIAM A. xNoor,

LABORATORIES, INCORPORATED, OF NEW YORK, N. Y., A.

Application, filed December 4, 1929.

This invention relates to synchronous communication systems, and particularly to high speed printing telegraph systems.

The general object of the invention isto maintain in a positive manner and with exactness, synchronism between transmitting and receiving apparatus at separated points.

.A more specific object is to continuously maintain s'ynchronism by causing the receiving apparatus to run as nearly as possible at the same speed as that of theass'ociated transmitting apparatus. This is in contrast to systems in which the motor of the receiver runs at a speed inherently different from that of the transmitter and the receiving brushes are reset to obtain approximate synchronism I across the input two vacuum tubes,

plied to effect the desired correction.

- the present invention a with the transmitter, or 1n which'the receiving distributor averages the same speed as the transmitter.

A feature of the invention is apparatus comprising a storing condenser connected of the vacuum fork circuit, which circuit is responsive to extremely small departures from synchrodirection for correcting. the In U. S. to W. A.'Knoop on is disclosed an arreceiving apparatus.

February 18, 1930, there rangement in which a series of short impulses of the one sign are produced and split by means of a distributor to produce effects upon which are differently ap By circuit arrangementsinacoordance with desirable simplification and other attendant changes are secured.

This is done by asystem in which impulses ofboth positive and negativesign are produced in response to-each'incoming signal impulse and impressed on the vacuum tube tuning'fork circuit. A distributorwhich effects this production of the positive and negative ulses has alternate segments intercom-1 necte to form two groups and as the distributor brush rotates over adjacent segments the impulses so produced have either a preponderanoe of an equality o voltage therebetween in ,ac-

Wi'dancewith-whether the'loeal distributor is running fast,slow or in phase, The equal two adjacent segments tube tuning :characterlstic of the negative itive or negative voltage, or

CF HEMPSTEAD, NEW YORK, ASSIGNOR 1'0 BELL TELEPHONE CORPORATION OF NEW SYNGHBONIZJNG SYSTEM Serial No. 411,406.

or unequal impulses are impressed together upon a storing condenser, wherein the former neutralize each other and the latter causes the excess voltage to be applied directly to the tuning fork circuit without the use of correctingvacuum tubes. In the drawings, Fig. 1 shows a correction circuit wherein two polarized relays of the two-position type operate in response to the incoming signal impulses, one of the relays having a sufiicient delay characteristic to remainnon-responsive until the distributor brush has had time to engage portions of and to thereby transmit two impulses of opposite polarities to the fork circuit; I

Fig. 2 shows a plate current-grid potential characteristic of the pick-up vacuum tube of the tuning fork circuit of Fig; 1;

Fig. 3 shows the operatiorr curves of the circuit of Fig. 1; Fig. 4 shows a modification of Fig. 1 wherein a pair of transformer (preferably having high permeability magnetic cores at low magnetizing forces) are employed to convert the incoming signal current impulses to voltage impulses, which in turn are impressed over a negative C modulator tube and a different-ial impulse relay, the relay being adapted to transmit the correcting lmpulses to the fork circuit; Fig. 5 is the I C modulator tube of Fig. 4;

Fig. 6 is a modification of Fig. 4. wherein the transformers and the negative 0 modulator tube are replaced by an unbiased polarized relay;

' Fig. 7 is a modification of Fig. '6, whereir: the impulse relay for controlling the correcting impulses impressed on the tuning fork circuit is of the make-before-break type;

(ntit shown) whereln the incoming signals are regenerated in a manner to give a satisplate current-grid potentialnals.

factory reproduction of the transmitted sig- The circuit 11 includes relays 12 and 13, both of which are of the unbiased polarized type. A condenser 14 is connected across the windings of relay 13 t6 give the latter a delayed action whereby the relay is made slow to operate in contrast to relay 12.

The aramature of relay 13 is connected to rotary distributor CD and the armature of re lay 12 is'connected to one side of the input circuit of the vacuum tube circuit which is arranged to control the vibration of tuning fork 15. In response to each change in polarity of the incoming signals, relay 12 operates to either of its contacts depending upon the polarity of the incoming signal impulse, and shortly thereafter relay 13 also operates to the correspondin contact but not until the distributor brush 1% one to the other of two adjacent segments.

The rotary distributor of which only the cor- :19 is connected magnetic field of the vibrating fork 15' relay 28,

recting rings are shown comprises a continuous ring 16, a segmented ring 17 and a rotat able brush 18. Ring 17 has its alternate segments interconnected to form two groups which are respectively connected to opposite poles of battery 19. The mid-tap of battery to the other side of the input circuit of the vacuum tube tuning fork circuit. I

The vacuum tube circuit may be of the type disclosed in U. S. Patent 1,809,832, granted to A. M. Curtis equivalent. In the circuit here illustrated a pick-up magnet, 20 is arranged in the and is adapted to impress the frequency of the fork on a pic --up vacuum tube 21, transjformer 22, a fork drive vacuum tube 23 and a relay drive vacuum tube 24, the grids of the two last mentioned tubes being connected in parallel. Fork frequency current in the output circuit 'of vacuum tube 23 flows through transformer 25 and the winding of magnet 26 in series taneously, the fork frequency current in the output circuit 'of vacuum tube 24 flows through transformer 27 and the windings of whereby the relay operates at th frequency of the fork. The operation of relay 28 causes battery to be alternately applied-at the frequency of the fork to the two windings of the phonic wheel motor '29, whichdrivesbrush18.

When the distributor CD is in synchronism with the incoming signals brush 1 8-is arranged topass over equal portions of an two adjacent segments of ring 17 at the time a signal impulse is received, so that equal amounts of positive and negative charge are successively applied by brush 18 over the armature of relay 13, either of the relay contacts, the opposite contact and the armature of relay 12, to storing bondenser 30. Con

denser 30 which is of a relatively high capac- 1n the average grid potential or ope as passed from on June 16,1931 or its to drive fork .15. Simul-,

the incoming signals.

ity, say of aboutsl microfarad, is connected across the in ut'circuit of vacuum tube Therefore, w en equal voltages of opposite polarity are applied to condenser 30 in rapid succession, they will neturalize each other and no change will be effected in the normal fork frequenc current in the input ciricmt of vacuum tu e 21. But should the charge of either polarity predominate, a charge of the predominating polarity will be superimposed on the normal fork frequency current to cause an increase or decrease, depending on the polarity of the predominating voltage, rating point of the pick-up tube 21. This increases or decreases the output energy of tube 21 and tube 23 and this increases or decreases the amplitude of vibration of fork 15. The damping of fork 15 dependsupon the amplitude of vibration and the frequency depends (to a second order degree) on the damping. When the amplitude of. vibration increases the damping increases and the frequency decreases.

There is in the input circuit of vacuum tube 21 a negative battery 31 and a relatively high resistance 32 of a value, say, of about 2 megohms. The C battery 1s of such voltage as to bring the operating point of vacuum tube 21 to approximately the middle of the curved portion of the plate currentgrid potential characteristic of the tube, as indicated in Fig. 2.

The operation of the circuit arran ement of Fig. 1 may be readilyunderstood Ay ref;

erence to Fig. 3, wherein the curves inclusive, shows the effects of the incoming resents the operation of the armatureof relay 12 in response to the signal impulses shown in curve A, the armature moving to its right hand contact in response to impulses of positive polarity and to its left hand contact in response to impulses of negative polarity. Curve 0 represents the o eration of the slow-acting relay 13, whereo the armature operates correspondingly with the armature of relay 12, but at a slight interval later. Curve D represents the impulses produced when brush 18 passes over portions of any two adjacentsegments of ring 17, it being noted that positive and negative im ulses are produced at every change of polarity of The positive and negative impulses produced by the distributor y occur during the intervalbetween the operation of relays 12 and .13 and therefore are very short. When the distributor is in synchronism with the incoming signals these impulses will be equal, as indicated by the first pair of impulses shown in curve D. Should the distributor be coming si segment connected to positive running ahead/of the in-; als brush 18 will cover a greater portion o th battery than that of I the second E shows the corresponding efiects or impulses.

the segment connected to'negative battery and therefore the im-' pulses produce will be like those shown in roup of impulses in curve D, but should the %rush 18 fall behind the incoming signals brush 18 will cover the greater ortion of the segment connected to negative attery than that connected to positive and the resultant impulses will be like those shown in the third group shown in curve D. Curve of the impulses of curve D upon condenser 30. The general principles of the invention may be applied to any driving mechanism which may have its speed corrected by inequality of normally equal positive charges Fig. 4 is a modification of Fig. 1, wherein the correcting'circuit 11 terminates in the windings of two transformers 41 and 42 which preferably have high permeability cores of the type disclosed in copending application of E. T. Burton,

Serial No. 280,709, filed May 26, 1928, corresponding to British Patent 312,338, the complete specification of which was:=accepted June 10, 1930. These transformers are equipped with cores of nickeliron alloys of high initial permeability,

slightly above or which have highpermeability at low maghave a magnetic circuit which becomes overloaded at low amplitudes of the signaling current. Therefore, a signal wave of slowly received in the transformers produces in the secondary windings thereof a wave of short discrete impulses, which occur while the magnetizing force. is passing through values below zero. By biasing the transformers magnetically in opposite directions, the intervals in which the sharp impulses occur, are shifted to the higher values of signal current, so that .two impulses are produced durlng the rise and fall of a signal wave on either the positive or negative side of the zero value. The impulses so produced'by each signal wave are of opposite I polarity and are produced in one or the other of the secondary windings,

, depending upon the polarity or direction of the signal wave, that is, those caused by a positive waveare produced in one winding and those caused by a negative wave are produced in the other winding. For an illustration of how thesecondary impulsesoccur, reference may be made to British Patent 312,338 supra. The secondary windings areconnected in series, but reversed with respect to each other in order to invert the impulses in one winding,

thereby obtaining a positive impulse at the beginning and a negative impulse at the end of each signal wave, or half cycle, regardless of the polarity of the wave. These volta e impulses are each impressed on vacuum tu 43 which serves in conjunction with battery 44, as-an amplifier, whereby the impulses of varying intensities when sitive' polarity only are capable of producmg an effective current in the plate circuit of the tube. As the grid is made sufficiently negative to normally block space current, negative impulses circuit of the tube includes-the right hand winding of rela 45 and battery 46; Relay 45 isof the di erential type, having its armature normally in the position shown, due to the current normally assing through the circuit which includes attery 46, the left hand winding of the relay and adjustable resistance 47. Each time a positive voltage impulse is received in the input circuit of tube 43 the plate current flowing through the right hand winding of relay 45 rises to a value whereat the normal current flowing through resistance 47 is overcome and the relay momentarily operates its armature to its ri ht hand contact. Should the corrector istributor CD be in synchronism with the incoming signals the distributor brush will be passing over equal portions of any two adjacent segments, during the interval in which the relay armature is in engagement with its right hand contact, thereby permitting equal current impulses of positive and negative polarity to be ap lied to the vacuum tube tuning fork circuit shown diagrammatically by block X) in the same manner as descri above for Fig. 1. Should the corrector distributor be running ahead or behind the incoming signals the distributor brush will be engaging unequal portions of two adjacent segments, thereby causing unequal current impulses of negative and positive polarity to be applied to the fork circuit whereby the speed of vibration of the fork'and motor relay are accelerated or retarded in the manner hereinbefore described.

, Fig. 5 shows the plate current-grid otential characteristic of the amplifier tu e 43, the battery 44 being ofsuch value as to place the operating point of the tube near the lower end of the characteristic.

Fig. 6 shows a modification of" 4,

wherein the correcting circuit 11 terminates in relay 51, which is of'the unbiased polarized type. Relay 51 is normally in engagement with either of its contacts,'whereby a circuit is closed through the left hand winding of relay 52, also of the unbiased polarized type, to battery 53. Relay ating in response to every ity of the incoming signals, changes the position of its'armature and in the interval between breaking one contact and making the other, the shunt path across battery 53, which includes variable resistance 54 and the right hand winding of relay 52, becomes effective to operate relay 52 to its right hand contact. Relay 52 has its windings arranged have no effect. The plate 51 in oper-v change of polardas in diiferential relation and the current fiow- Should the brush'of correctin distributor be in synchronism with t e incoming signals, equal current impulses of positive and negatlve'polarity will be appliedto the vacuum tube tuning fork circuit (shown diagrammatically by block X) when the armature of relay 52 momentarily engages its right'hand contact, but should this synchronism be lacking, the current impulses produced through distributor CD equal and thereby effect the desired correction of the speed of vibration of the tuning fork and the motor relay as described above for Fig. 1.

Fig. 7 is a modification ofFig. 6, wherein the correcting circuit 11 terminates in an unbiased polarized relay 61. The left hand contact is connected to the positive pole of battery 62 and the relay armature is connected to one side the winding of a non-polar relay 63, which has its other side connected to the negative pole of battery 62. Relay 63 has armatures of the make-before-break type where- Normally spring of the armature 64 is in engageable relation with spring 65. Spring is in engageable relation with spring 66 and spring 66 is in engageable relation with spring 67 which is connected tothe corrector distributor CD. 67 is in engagement with spring 66, but spring 66 is out of engagement with spring 65 and spring '65 is out of engagement with armature .64. When the po arity of the incoming signals changes from negative to positive the operating circuit for relay 63 closes and armature 64 is attracted and thereby pushes spring 65 into engagement with spring-66 to break contact tween'springs 66 and 67 and in the interval tween the interengagement of springs 65 and 66 and the disengagement of springs 66 and 67 current impulses of negative'and positive polarity are transmitted to the vacuum tube tuning fork circuit (shown dia grammatically by block X) in a manner hereinbefore described. The impulses trans mitted to the fork circuit are equal if the distributor brush is in phase with the incoming signal, but should there be a difl'erence in phase relation the impulses will be of *50 unequal lengths to effect the desired cor- L rection-in the speed of vibration of the tuntwo contacts, one of which is arranged to be.

in fork and the armature of the motor re ay. Y v

Fig 8 shows a modification of Fig. '1,

" wherein .correctin circuit 11 includes the 1 which is of the biased winding of relay polarized type.

three positions and is resp tive and negative incoming signals. The relay has attached to its armature a weighted arm in engageable relation on each side with Relay 71 is arranged for engaged by the arm before the other. Therefore, in response to each change of signal polarity the armature causesboth contacts will be un- .,pulses.

onsive to both posion either side to be interconnected 'to com-' pletefor a short interval an operating-path to the fork circuit (shown diagrammatically by block X). The outer contact is connected tothe correct distributor CD. Should the distributor-brush be in phase with the incoming signals, it will be passing over equal portions of any two adjacent segments at the time both contacts on either side of the arm are interconnected,thereby sending equal current impulses of positive and negative polarity to the fork circuit as hereinbefore described, phase, then the current im ulses will be of unequal lengths and will t desired correction.

\ What is claimed is:

1. A method of causing a synchronous device to remain closely in phase with incoming current impulses which consists in generating a pair of impulses of opposite polarities in response to an incoming impulse, superimposing said pair of impulses of opposite polarities-in rapid succession on an. alternating current of substantially constant :fre-

uency for driving said device. andiutlhzmg t e preponderance of one polarity in each of said pairs of impulses to alter the frequency of said alternatlng current to thereby eflect continuous correction for synchronism and phase relation.

2. The method of causin a synchronous device to remain closely in p ase with incoming current impulses, which {comprises producing a plurality of impulses of opposite polarities in response to an incoming 11 npulse, impressing said impulses of opposite polarities in rapid succession on an energy storing element whereby any: difi'eren'ce 1n the magnitudes of said impulses is reta ned on said storing element as a charge of positive or negative polarity depending on the predominating polarity of adjacent impulses of opposite polarities, and utillzin'g and charges to accelerate or decelerate, as deslred, said device to the speed of. the incoming 1m- 3. In a synchronous receiving system, a combination of elements for correcting for slight departures from synchronism compr1sing means for converting each received current impulse into a plurality of impulses of opposite polarities, a synchronous device, a source of constant frequency for drivingsaid device, and storing means for receiving said impulses of opposite polarities in rapid succession and for impressing a charge resulting from any difference in the ma itudes of two succeeding impulses, in a' irection tending torestore synchronism.

4. A system for correcting for. phase deereby eifect the but should the brush be out of v parture inlsynchronous apparatus comprisone of said received impulses, means for impressing I utilizing the preponderance of one said impulses ofopposite Folarities on said driving means, and means or utilizin the preponderance of an impulse of one po arityoveran impulse of the other polaritygto correctthe'speed of said driving means w en a. slight departure in phase relation occurs. 7 5. A

ehronous apor receiving a paratus comprising means series ofincoming impulses with which a loe synchronized, means cal rotary device is to for driving said local rotary device, other rotatable means for producing impulses of opposite polarities in response to each incoming im ulse, means for impressing said impulses o opposite polarities on said drivin means, and capacity storing means for polarity over the other polarit impulses to correct t e speed of said driving means when a slight departure in phase relation occurs.

' 6. In a synchronous communication system, means for producing synchronizing impulses of op osite polarities from a received signal impu se, electromagnetic means for operating said impulse producing means,a vibratin element for controlling the operation of sai electromagnetic means and a storing element responsive to said synchronizing impulses for varying the frequency of vibration of said .vibrating element in accordance with the speed of the incoming signal impulses.

7. In a synchronous telegraph system, a rotary distributor for producing synchronizing impulses of opposite polarities from a received signal impulse, a motor for operating said distributor, a vacuum tube tunin fork circuit for controlling the operation 0 said motor, and a condenser connected across the input circuit of said vacuum tube circuit and responsive to said synchronizing impulses of opposite polarity for regulating the speed I of said motor in accordance with the speed of the incoming signal impulses. 8. In a synchronous impulse receiving system, a combination of elements for correcting 'for slight departures from synchronism between a rotary receiving device and incom ing signal impulses, comprising means in: cluding mechanically moving parts arranged to generate impulses of opposite polarities sifinal impulse, and means for utilizing any di erence inthe magnitude or duration of two generated impulses of opposite polarities to correct for synchronism.

, 9. In a synchronous impulse receiving system, a combination of elements for correcting for slight departures from synchronismbetween a rotating receiving device and the one incoming stem for correction of phase dc-' parture, owever small, n s

of adjacent produced.

incomin signal impulses, comprising a plurality 0 devices '0 crating under the control of received impu s and havin different a contro ing current to flow in response to signal impulse in the'interim between the mstant of operation of said devices by the same mpulse and means for utilizing said controlling current to correct said rotating device to synchronism with the incoming im ulses.

.- 10. A sync tem, according to claim 9, wherein the operating devices are electromagnetic relays at least f one of which-is provided with means for adju'sting its time of operation as compared to the other.

11. In a synchronous impulse receiving system arranged to recelve polar signals, a rotating receiving device, means for converting each incoming signal impulse into a.

plurality of impulses of opposite (polarities, means for eliminating the converte impulses of one polarity, means for changing each of the converted impulses of the other polarity into a pair of impulses of opposite polarities,

and means for utilizing any difference in the.

magnitude or duration of two of the last mentioned impulses of opposite polarities to cor-'- rect for any slight departures from synchroronous lmp'ulse receiving sys nism between said device and the incoming signal impulses. I

12. In a s chronous impulse receiving system accor ing means for converting each of the incoming signal impulses into a plurality of "impulses of opposite polarities is an oppositely iased pair of transformers having core material of a high permeability at the very low magnetizing forces. w

3. In a synchronous impulse -16C61V1Ilg system, a rotating receiving device, an instrumentality responsive to the incoming signal impulses to produce, in'conjunction with said rotating device and during the interval of its movement, two current impulses of oposite polarities, controlled by any or duration of the two impulses of opposite polarities to correct forany departure from synchronism of said rotating device with the incoming signal impulses.

14. In a synchronous impulsz receiving system, according to claim 13,- herein the said instrumentality com rises an electromagnetic relay of the makefore-break t In testimony whereof, I hereunto subscn to claim 11, wherein the and correcting mechanism difierence in the magnitude 

